Fundamental Electronics

1. BACK UP SYSTEMS
CHAPTER 16.3
CURRENT CAPACITY & RATING OF BATTERY
By
Dinesh Kumar Sarda

2. CONVERSION OF DEGREE FARHENITE TO DEGREE
CELCIUS
T(°F) = T(°C) × 9/5 + 32
Ex : 0°C = 32 °F

3. TECHNICAL SPECIFICATIONS ??
A Technical Product Specification is a
document that provides critical defining
information about a product
and can include identification of the
manufacturer; a list of rules, bans and
standards that apply to the item,
design specifications and product images

4. VOLTAGE RATING OF A BATTERY
The factors that affect the VOLTAGE RATING of
a cell are the material the electrodes are
made of and the composition of the
electrolyte.

5. CURRENT RATING OF A BATTERY
• The factors that affect the CURRENT CAPACITY of a cell
are the size of the electrodes, the distance between
them in a solution of electrolyte, and the temperature.
• The current capacity of a cell is expressed in AMPERE-
HOURS. Ampere-hours of a cell is the measurement of
current capacity that indicates the amount of current
that will flow through a circuit in a certain amount of
time.
• Ex: 100 Ah means 100 amperes can be supplied for 1
hour.

6. C and E Rates
 A C-rate is a measure of the rate at which a
battery is discharged relative to its maximum
capacity.
 A 1C rate means that the discharge current
will discharge the entire battery in 1 hour.
For a battery with a capacity of 100 Amp-hrs,
this equates to a discharge current of 100
Amps.
 A 5C rate for this battery would be 500
Amps, and a C/2 rate would be 50 Amps.

7.  E-rate describes the discharge power.
 A 1E rate is the discharge power to
discharge the entire battery in 1 hour
Battery amp-hour, watt-hour and C rating
tutorial.mp4

8. Battery Condition
This section describes some of the variables
used to describe the present condition of a
battery.

9. State of Charge
(SOC)(%) – An expression of the present
battery capacity as a percentage of maximum
capacity. SOC is generally calculated using
current integration to determine the change in
battery capacity over time

10. Depth of Discharge
(DOD) (%) – The percentage of battery
capacity that has been discharged expressed
as a percentage of maximum capacity.
A discharge to at least 80 % DOD is referred to
as a deep discharge.

11. Terminal Voltage (V)
The voltage between the battery terminals
with load applied. Terminal voltage varies with
SOC and discharge/charge current.

12. Open-circuit voltage (V)
The voltage between the battery terminals
with no load applied. The open-circuit voltage
depends on the battery state of charge,
increases with state of charge.

13. Internal Resistance
The resistance within the battery, generally
different for charging and discharging, also
dependent on the battery state of charge. As
internal resistance increases, the battery
efficiency decreases and thermal stability is
reduced as more of the charging energy is
converted into heat.

14. Nominal Voltage (V)
The reported or reference voltage of
the battery, also sometimes thought
of as the “normal” voltage of the
battery.

15. Cut-off Voltage
The minimum allowable voltage. It
is this voltage that generally
defines the “empty” state of the
battery.

16. Capacity or Nominal Capacity (Ah for a specific C-rate)
The coulometric capacity, the total Amp-hours
available when the battery is discharged at a
certain discharge current (specified as a C-
rate) from 100 percent state-of-charge to the
cut-off voltage. Capacity is calculated by
multiplying the discharge current (in Amps) by
the discharge time (in hours) and decreases
with increasing C-rate.

17. Energy or Nominal Energy (Wh (for a specific C-rate))
The “energy capacity” of the battery, the total
Watt-hours available when the battery is
discharged at a certain discharge current
(specified as a C-rate) from 100 percent state-
of-charge to the cut-off voltage. Energy is
calculated by multiplying the discharge power
(in Watts) by the discharge time (in hours).
Like capacity, energy decreases with
increasing C-rate.

18. Cycle Life (number for a specific DOD)
The number of discharge-charge cycles the
battery can experience before it fails to meet
specific performance criteria. Cycle life is
estimated for specific charge and discharge
conditions. The actual operating life of the
battery is affected by the rate and depth of
cycles and by other conditions such as
temperature and humidity. The higher the
DOD, the lower the cycle life.

19. Specific Energy (Wh/kg)
The nominal battery energy per unit mass,
sometimes referred to as the gravimetric
energy density. Specific energy is a
characteristic of the battery chemistry and
packaging. Along with the energy
consumption of the vehicle, it determines the
battery weight required to achieve a given
electric range.

20. Specific Power (W/kg)
The maximum available power per unit mass.
Specific power is a characteristic of the battery
chemistry and packaging. It determines the
battery weight required to achieve a given
performance target.

21. Energy Density (Wh/L)
The nominal battery energy
per unit volume, sometimes
referred to as the volumetric
energy density.

22. Power Density (W/L)
The maximum available power per unit
volume.

23. Maximum Continuous Discharge Current
The maximum current at which the battery can
be discharged continuously. This limit is
usually defined by the battery manufacturer in
order to prevent excessive discharge rates that
would damage the battery or reduce its
capacity.

24. Maximum 30-sec Discharge Pulse Current
The maximum current at which the battery can
be discharged for pulses of up to 30 seconds.
This limit is usually defined by the battery
manufacturer in order to prevent excessive
discharge rates that would damage the
battery or reduce its capacity.

25. Charge Voltage
The voltage that the battery is charged to when
charged to full capacity. Charging schemes
generally consist of a constant current charging
until the battery voltage reaching the charge
voltage, then constant voltage charging,
allowing the charge current to taper until it is
very small.

26. Float Voltage
The voltage at which the battery is maintained
after being charge to 100 percent SOC to
maintain that capacity by compensating for
self-discharge of the battery.

27. (Recommended) Charge Current
The ideal current at which the battery is
initially charged (to roughly 70 percent SOC)
under constant charging scheme before
transitioning into constant voltage charging.

28. Internal Resistance
 The internal resistance (IR) of a battery is defined as
the opposition to the flow of current within the
battery.
There are two basic components that impact
the internal resistance of a battery; they are electronic
resistance and ionic resistance.
The resistance within the battery, is generally different
for charging and discharging.

30. Cold-Cranking Amperes
Every automotive battery must be able to supply
electrical power to crank the engine in cold weather
and still provide battery voltage high enough to
operate the ignition system for starting.
Cold cranking power of a battery is the numbers of
amperes that can be supplied by a battery at 0˚F(-
18˚C) for 30 sec while the battery still maintains a
voltage of 1.2 V per cell or higher
Cold Cranking performance is called cold cranking
amperes(CCA)

31. Cranking Amperes
The designation CA refers to the number of
amperes that can be supplied by a battery at
32°F (0°C).

32. DEEP CYCLING
 Deep cycling is almost fully discharging a
battery and then completely recharging it.
Charging is hard on batteries because the
internal heat generated can cause plate
warpage, so these specially designed batteries
use thicker plate grids that resist warpage.

37. PRACTICAL TECH SPEC SHEET
• HBL Approved GTP.pdf